Physics basics

Physics Basics – Study Notes for Puducherry TET

Subject: General Awareness & Current Affairs
Topic: Physics Basics

1. What is Physics?

• Physics is the science that studies how things move and interact.
• It looks at energy, force, motion, heat, light, and electricity.
• Everyday life – a moving car, a light bulb, a hot cup of tea – all involve physics.

2. Units & Measurement

• Metric system is used everywhere in India.
• Remember: 1 J = 1 N × 1 m.

3. Motion

• Speed = distance ÷ time.
  Example: A student walks 10 m in 5 s → speed = 2 m/s.
• Direction tells where you’re going.
• Uniform motion – same speed, straight line.
• Acceleration – change in speed.
  Example: A car speeding from 0 to 20 km/h in 5 s.

4. Force

• A push or pull that can change motion or shape.
• Gravity pulls everything toward the Earth.
• Friction is the resistance that slows motion (e.g., rubbing hands together).
• Hooke’s Law (spring): force = spring constant × stretch.
  Tiny example: Pull a rubber band – the more you pull, the stronger the pull back.

5. Energy & Work

• Energy is the ability to do work.
  • Kinetic energy – moving objects.
  • Potential energy – stored, e.g., a raised book.
• Work = Force × distance in the direction of the force.
  Example: Lifting a 2 kg book 2 m → work = 2 kg × 2 m × 9.8 m/s² ≈ 40 J.
• Conservation of Energy – energy cannot be created or destroyed, only changed.

6. Power

• Power = Work ÷ time.
  Example: A 60 W bulb uses 60 joules of energy each second.
• High power = fast work (e.g., a race car).
• Low power = slow work (e.g., a kettle heating water).

7. Thermodynamics (Heat)

• Heat = energy in motion of molecules.
• Temperature measures average motion; hotter = faster motion.
• Heat transfer:
  • Conduction – direct contact (metal spoon in hot soup).
  • Convection – fluid movement (steam rising).
  • Radiation – waves (sunlight warming your skin).
• First law of thermodynamics – energy balance in a system.

8. Electricity & Magnetism

• Electricity – flow of tiny charged particles (electrons).
  • Voltage (V) = push that moves electrons.
  • Current (I) = amount of electrons passing per second.
  • Resistance (R) = opposition to flow (like a narrow pipe).
• Ohm’s Law: V = I × R.
  Tiny example: A 3 V battery, 0.5 Ω resistor → current = 6 A.
• Magnetism – magnetic fields from moving charges.
  • A fridge magnet sticks because it has a magnetic field.
  • Electromagnets: running current through wire creates a magnet (used in motors).

9. Modern Physics (Brief)

• Special Relativity – at very high speeds, time and length change slightly.
  Analogy: A clock moves slower if it runs very fast.
• Quantum Physics – at very small scales, energy comes in packets (quanta).
  Tiny example: Light can be seen as tiny “photons” (light particles).
• Applications – computers, GPS, MRI machines, solar panels.

10. Key Indian Institutions & Recent Developments